Process for the treating of hydrocarbon materials



May 17, 1932. P; K. FROLICH NU Q 0 Nu Filed 10st. 14. 1927 PROCESS FOR THE TREATING OF HYDROCARBON MATERIALS Qwwamtoz Patented May 17, 1932 UNITED STATES PATENT orrrce PER K. FROLIOH, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR IO STANDARD DEVELOPMENT COMPANY, A' CORPORATION OF DELAWARE Pnocnss r013. THE TREATING or mnocamaoiv Application filed October 14, 1927. Serial N0. 220,076-

The present invention relates to the art of treating hydrocarbon materials to form valuable liquid products and more specifically to a process 'for oxidizing hydrocarbons with air to form substantial yields of alcohols, aldehydes, acids and other oxygen-containing compounds. My-process and the apparatus for carrying out the process willlbe.

fully understood from the following'description and the drawing, which illustrates 'one form of apparatus suitable for that purpose.

The drawing is a semidiagrammatic view in elevation of an apparatus constructed according to my invention and illustrates the flow of materials through the apparatus.

In a previous application, Serial No.

r 190,728, filed May 12, 1927, by the-present inventor and another, a process for the direct oxidation of the lower boiling hydrocarbons with oxygen or oxygen-containing gases to form alcohols, acids, aldehydes, and other i oxygen-containing compounds, was disclosed.

My present invention relates specifically to an improved method of oxidizing hydrocarbons with air or other oxidizing gases containing diluent gas such as nitrogen, carbon monoxide, or carbon dioxide.

The use of air for the oxidation of hydrocarbons is economically advantageous because of its availability. It is also highly advantageous to recycle the unoxidized hydrocarbons through a reaction zone if one is to obtain large yields. My present invention comprises a method for economically carry- 7 ing out the oxidation with air as the oxygencontaming gas. i

Referring to the drawing, the reference character 1 designates a high pressure source of hydrocarbons which may. be normally 40 either liquid or gas, a single pure compound, or a hydrocarbon-containing mixture. This raw material, which will hereafter be termed hydrocarbon, is fed by a pipe 2 to a manifold 3 and then to a plurahty of coils a, b, a, and d, which are carefully dlstributed throughout the interior of a reactor and in which the hydrocarbon is preheated. The reactor may be of any suitable design but is preferably a heavy steelshell adapted to withstand pressures in excess of 3,000 lbs. per square inch and a temperature of 600 C. or higher. The reactor is suitably lagged'and may be fitted with other heat exchanging coils in addition to a, b, 0, and cl, but which have not been shown on the drawing forsake of simplicity. The body of the reactor may be otherwise empty or it may be partially filled with catalytic material, the nature of which was disclosed in application Serial No. 190,728. The

hydrocarbon feed is distributed throughout the coils a, b, 0, and (1 so as to absorb the heat evolved by oxidation and to maintain all parts of the reactor at approximately'the same temperature, which is predetermined and called the reactor temperature. Part of the hydrocarbon is passed through a line E to a heat exchanger F and is there preheated.

by the reaction products from the reactor as will be described below, and a part of the hydrocarbon may be by-passed through line E.

i The preheated hydrocarbon passes toa manifold 5 and is thence conducted to a coil 6, wherein the hydrocarbon is heated to a temperature somewhat below that of the reactor and is thendischarged into a mixing pipe 7. A by-pass line 6 is provided so that 4 all or part of the hydrocarbon may be shunted around the coil 6 after the reactor has reached 7 its proper temperature. Air is compressed by a suitable compressor 8 and is also discharged into mixmg pipe ,7, wherein it is thoroughly mixed with the hydrocarbon.-

The mixture is then discharged into the reactor 4 and the heat of reaction immediately raises the temperature to the predetermined degree. If desired, part of the air may flow through pipe 9' and enter the reactor by a plurality of branch ipes a, b, and of in re P 7 V g ulated quantities.

. may

The mixture discharged from the reactor is cooled in exchanger 'F and a cooler is then discharged through a reduction valve 11 into the intermediate portion of a rectifying column 12, or any apparatus commonly used to se arate liquid and vapor.

of any preferred design but bellcap plate columns'are satisfactory. The column I may be fitted with-a cooling coil 13 in the upper portion, and a heating coil 14 at the base,

which may be an open steam coil, if desired.

'Nitrogen and other permanent gases escape from the top of column .12 by line 15 and are conducted to the base of a gas scrubbing tower 16into th'lower part of which the gas is discharged through a spray pipe 17. A suitable solvent is admitted to the upper part of tower 16 through a spray pipe 18 and in passing downwards extracts any normally liquid oxidation products and valuable gase ous oxidation products, such as formaldehyde, which may have escaped from column 12 with the permanent gases. carrying the extracted material then flows by line 19 to a tank 20. Permanent gases leave tower 16 by line 21 which is fitted with valve 22 to hold pressure on the system. The gas may be expanded to furnish work for compressing air, as will be readily understood.

The liquid flowing from the base of column 12 comprises liquid oxidation products and unoxidized liquid hydrocarbon and is conducted to a liquid scrubbing system 24, which charged by line 27 to the storage tank 20 or' to separate storage by line 28.

In the drawing a system using the same solvent for towers l6 and 24 is illustrated and a pump 29 is used to circulate the solvent through the towers by circulation line 30 but as will be readily understood, the recovery systems for the two towers may be separate and different solvents may be used. I prefer-to use the .same solvent for both towers and to withdraw the rich solvent from tank 20 by line 31 to a separation system (not shown), which may consist of rectifying stills. Fresh or stripped solvent may be admitted by line 32.

Unoxidized hydrocarbon rises in column 24 and is forced by pump 33 through line 34 to a tower -35'into which it is fed through spray pipe 36, An alkaline solution, for example caustic soda, is circulated through this tower by pump 37 and line 38 to dissolve the carbon dioxide from the unoxidized hydrocarbon. The solution is withdrawn at the The colunm' lower pressure.

The solvent base of tower 35 into a tank 39. Spent soda may be withdrawn by pipe 40 and fresh soda introduced by 41. The unoxidized hydrocarbon, freed of carbon dioxide, is withdrawn from the top of tower 35 and conducted back to tank 1 by pump 42 and line 43 for recirculation through the apparatus. This purification is desirable if ethane or methane is recirculated but can be dispensed with if only hydrocarbon heavier than ethane is recirculated since the carbon dioxide under these conditions can be drawn oil at line 21 with nitrogen, as will be understood.

In the operation of my process, the hydrocarbon'is under a pressure in excess of 1,000

lbs. per square inch and preferably between 1,500 and 3,500 lbs. per square inch. Air is fed at approximately equal pressure and the reactor is maintained under full or slightly The temperature of the reactor is preferably between 350 and 600 0., depending on thenature of the hydrocarbon and the specific catalyst used, as is fully discussed in the earlier application, Serial No. 190,728. The temperature-of the gases entering the reactor can be regulated as desired ,by suitable adjustment of the apparatus described above, and the temperature within the reactor may be carefully regulated, not only by the coils a, b, c, and d, but also by adjustmerit of the proportion of air to hydrocarbon.

In starting up the process, it is advisable to circulate only hydrocarbon until temperature is raised and then to introduce air to build up the concentration of oxygen to thedesired value. As a maximum, I may useone atom of oxygen per mol of hydrocarbon in the feed mixture and I preferably operate with a lower proportion of oxygen. The percent of oxygen in the feed is often below 10% and sometimes below 5%, since lower percentages appear to cause less waste by formation of CO and CO and any danger of explosion by gas pockets is diminished, as will be understoo As described in application, Serial No. 190,728, the rate of flow of the material through the reactor is of importance. The rate of flow'is expressed by two methods. The space velocity is conveniently calculated and expressed in the units, litres of gas, at standard conditions of temperature and pressure, per hour, per cubic centimeter of free reactor volume and this rate should not be below 4.0. Surface velocity is likewise expressed at litres of gas at standard conditions of temperature and pressure, per hour, per square centimeter of superficial catalytic surface. On this basis the surface velocity should be above .20 litres per hour persquare centimeter. Preferably the rate of flow should be considerably higher. I have increased the s ace velocity about 80 litres per hour per on ie centimeter of reactor volume and surface velocity above 7.90 litres per hour per square centimeter of superficial catalytic surface, and such velocities are desirable.

For separation of the diluent gas, the oxidized and unoxidized hydrocarbon I prefer to first use a rectifying tower as illustrated by 12in the drawing. In this tower the nitrogen, may be easily separated from the normally liquid oxidation products and unoxidized hydrocarbon which is to be recycled.

Pressure and temperature conditions in tower- 12 vary somewhat with the nature of the hydrocarbon, but in general pressure and temperature should be so related that coil '13 will condense the lightest hydrocarbon which is to be recycled through the reactor, and

temperature at coil 14 should be sufficiently high to boil the liquid under the prev-ailing high as possible. I contemplate operating pressures up to 50 or 60 atmospheres with a temperature preferably below atmospheric at the top of column 12. At the base of the column temperature" may be from about 100 C. to +200 C. If methane is to be recycled a refrigerant capable of producing a very low temperature-must be used in coil 13 as will be understood. While I prefer to use 'a rectifying column such as tower 12, I might alternatively use a 'drum or the like for separation of gas and liquid and with such equipment a pressure above 60 atmospheres may be used. Wh-ile I prefer to make a complete separation of nitrogen from the hydrocarbon and to recover all hydrocarbonfrom nitrogen it may be economical not to attempt to obtain complete separation since to do so would require very low temperatures as will be apparent. For the solvent in towers 16 and 24 I prefer to use a. solvent heavier than the hydrocarbons and immiscible therewith. I contemplate the use of substances containing an hydroxyl group such as water, glycerine, ethylene glycol, or methanol, or mixtures of these with each other or other substances. A solvent lighter than the hydrocarbon-might also be used and in'this case the hydrocarbon would be added at thetop of the column, as will be understood. 1

As an illustration of the operation of my process, the following example is given of the oxidation of butane with air. A mixture of substantially pure butane and air was passed through a reactor partially filled with nickel wire catalyst. The oxygen concentration in the mixture was 4.9%, pressure 2400 lbs. per square inch and temperature approximately 430 C. Space velocity was 83.8 and surface velocity 7.95, both in the units above defined. The yield of liquid was 18 cubic centimeters for each 100 litres of butane gas by a single passage through the reactor, and about 55.1% of the oxygen went to normally liquid organic oxidation products. The liquid. on

fractional distillatlon showed the following composition:

Boiling range: Y 4 Up to 53 C. 50% acetaldehydeand 50% propionaldehyde (ap.

prox.) 3%

53-60 acetone 2 60-70 methanol 6 -7 8 95% ethanol, 5% water.-- 16 78-89 78% propanol, 22% water 31. 89-96 63% butanol, 37% water 5 96up acetic acid, propyl acetate and water 37 Chemical analyses ofthe liquid products gave the following results:

Acetic acid, by volume; 1 8.1

Propyl acetate, by volume 6.0

My process may be used for the oxidation of various hydrocarbons such as ethane, propane, butane, pentane, and the like. Methane and/or higher boiling hydrocarbons or mixtures thereof may also be present, but it is especially adapted for those hydrocarbons individually named either in a pure state or in artificial mixtures or natural mixtures such as will occur in natural gas or coal gas or refinery gas or in the lighter lower boiling distillates or condensatessuch as casinghead gasoline or natural gas gasoline and the like. My'process is not to be limited by any theory of the mechanism of the process or .by any illustrative example, but only by the attached claims, in which -I wish to claim all novelty inherent in my invention.

I claim:

1. In a continuous process for obtaining normally liquid oxygen-containing products fromhydrocarbons comprising low boiling and normally gaseous hydrocarbons, the step of bringing together said hydrocarbons and a-irunder pressure in excess of 1,000 lbs. per square inch in a reaction zone, maintaining said zone at a predetermined temperature between 350 and 700 C. by circulation of a stream of fresh hydrocarbon therethrough in heat interchanging relation to the reactingv oxygen-containing products from the resultv ,ing products, together with hydrocarbon material, are obtained in liquid phase, and the diluent is obtained substantially entirel in the gaseous phase, separating the liquid fi 'om the. gas, separating the hydrocarbon material from the oxygen-containmg products and returning the hydrocarbon material to the proc- 3. In a process for obtaining liquid oxygencontaining products from readily liquefiable paraflinic hydrocarbons by direct oxidation with air, the steps of bringing such materials together under pressures in excess of 1,000

pounds per square inch and at temperatures between 350 and 600 (3., cooling the hot gases under substantially the same pressure to a temperature at which a liquid phase comprising normally liquid oxygen-containingproducts and hydrocarbons and a vapor phase comprising substantially permanent gases are obtained, separating the liquid from the gas, separating the unreacted hydrocarbon from the liquid and returning the hydrocarbons to the oxidation.

4. Process according to claim 3 in which the oxidation is carried out under pressure between 1500 and 3500 pounds per square inch in the presence of a catalytic material.

5. An im roved rocess for obtainingioxidation pro ucts ric in alcohols from readily condensable hydrocarbons which comprises solvent for such oxidation passing such hydrocarbons with air through an oxidation zone maintained at temperatures between 350 and 600 C. and under pressures in excess of 1,000 pounds per square inch, cooling the eflluent mixture under superatmos pherlc pressure wherebya condensate is produced, separating the condensate from the gases, extracting the oxidation products from the condensate by means of a suitable liquid roducts, and recycling the unoxidized hy rocarbons to the oxidation.

PEI?) K. FROLIOH. 

